The present invention relates to a brace for a patient's limb, and more particularly, to a brace which is used to apply a dynamic force to a jointed limb to stretch contracted tissue and increase range of motion.
When a joint is immobilized for a period of time, such as when a patient's limb is immobilized in a cast or splint in order to allow a broken bone to heal, connected tissue at the joint tends to shorten, resulting in a decreased range of motion at the joint. This condition is exacerbated based on the length of time which the joint is immobilized.
As referred to herein, connective tissue includes ligaments, tendons, joint capsules, and other related structures which are composed of collagenous and reticular fibers, elastic fibers, fibrin and ground substance. These components form a mesh work of attached fibers which are connected at intervals throughout the tissue, and the longer the distance between the points of attachment, the greater the range of motion. The attachments can release or shift in response to prolong tension, or additional attachments can develop at points of prolong contact. The length of the fibers between the attachments can also increase or decrease depending on the presence or absence of force.
The prior known devices include variable locking devices with turn buckles, screws or hanging weights on the patient to apply a force on the limb. Recently, dynamic splints have been developed which use rubber bands or coil springs to apply a force on the splint at the joint. The dynamic splints are worn over a period of time, such as when a patient is sleeping, in order to stretch the connected tissue by providing a prolonged, constant, low intensity stretching in order to develop the patient's full range of motion.
In one known device, the brace comprises two sections attached on either side of the joint and a spring tension device is connected directly to the joint to apply a spring tension force on the patient's limb. However, it can be difficult for the patient to access or adjust the spring tension device while the device is being worn, especially for arm braces.
Another similar device utilizes coil springs as the connection between two sections of a brace to provide a resistance force to motion.
In another known device, two cuffs are provided for attachment to a patient's limb with a tower attached between the two cuffs to provide a mechanical advantage for increasing range of motion of the joint. The tower is a box-like structure which includes a drive mechanism for loading and unloading the cuffs to apply force to the limb. However, the tower device is fairly large and may not be suited for long term wear by a patient, such as when a patient is sleeping.
It is also known in the art to put a rigid element including a turn buckle on the inside angle of a joint between two cuffs attached on either side of a joint of a patient's limb and use the turn buckle to vary the length to push or pull the limb segments relative to each other.
It would be desirable to provide a device which can be worn by a patient for a long period of time, such as overnight while the patient sleeps, which provides an adjustable, controlled amount of force to the limb to allow for a gradual stretching action. It would also be desirable to use a force adjusting mechanism which does not have to be reconfigured to apply a force in the opposite direction, such as when a joint must be worked in both directions to regain the full range of motion. Additionally, it would be advantageous to provide a device in which the location of the force applying mechanism can be adjusted to a position where it is easily accessible for adjustment by the patient or in a position where it will cause the least patient discomfort.